Pachytene

Q.

What are the sub-stages of prophase I of Meiosis I? Explain briefly.

Q. The appearance of recombination nodules on homologous chromosomes during meiosis characterizes:

1. Bivalent
2. Sites at which crossing over occurs
3. Synaptonemal complex
4. Terminalization

Q. Crossing over takes place between which chromatids and in which stage of the cell cycle?

1. Non-sister chromatids of non-homologous chromosome at zygotene stage of prophase-I
2. Non-sister chromatids of homologous chromosome at pachytene stage of prophase-I
3. Non-sister chromatids of homologous chromosome at zygotene stage of prophase I
4. Non-sister cromatids of non-homologous chromosomes at pachytene stage of prophase I

Q.

Chromosomes are arranged along the equator during:

1. Prophase

2. metaphase

3. anaphase

4. telophase

Q.

The enzyme recombinase is required at which stage of meiosis?

1. Zygotene

2. Diplotene

3. Pachytene

4. Diakinesis

Q. A bivalent of meiosis I consists of

1. Two chromatids and two centromeres.
2. Four chromatids and four centromeres.
3. Two chromatids and one centromere.
4. Four chromatids and two centromeres.

Q.

Name the stage of the cell cycle at which one of the following events occur:

(i) Chromosomes are moved to the spindle equator
(ii) Centromere splits and chromatids separate
(iii) Pairing between homologous chromosomes takes place
(iv) Crossing over between homologous chromosomes takes place

Q.

Differentiate between Mitotic prophase and Meiotic prophase I ?

Q. A bivalent consists of ______ pair/pairs sister chromatid/chromatids and ______ pair/pairs of homologous chromosomes.

1. one; two
2. two; two
3. two; one
4. four; two

Q. Lampbrush chromosomes are seen in which typical stage?

1. Mitotic anaphase
2. Meiotic prophase
3. Mitotic prophase
4. Mitotic metaphase

Q.

Can you recall meiosis and indicate at what stage a recombinant DNA is made?

Q.

Why is genetic recombination so important?

Q. Statement I: Synapsis is the process of pairing of homologous chromosomes.
Statement II: Crossing over occurs between sister chromatids of homologous chromosomes.
Which of the above statements are correct?

1. Only I
2. Only II
3. Both I and II
4. Both the statements are wrong

Q. At which stage of Meiosis I does crossing over occur?

1. Lepoptene
2. Zygotene
3. Pachytene
4. Diplotene

Q.

Recombinase enzyme is involved during

1. diplotene

2. diakinesis

3. pachytene

4. zygotene

Q.

Recombinase enzyme is involved during

1. diplotene

2. diakinesis

3. pachytene

4. zygotene

Q.

Are Barr bodies heterochromatin?

Q.

How many steps are in meiosis?

Q.

How much is one map unit for expressing distance between genes in a chromosome

Q.

Identify the stage of cell division.

Homologous chromosomes (bivalents) are aligned at the equatorial plate?

Q. What are the various causes of variation?

Q. Match the stages of meiosis in column I to their characteristic features in column II and select the correct option:

Column I	Column II
A. Pachytene	(i) Synapsis
B. Anaphase I	(ii) Terminalisation of chiasmata
C. Diakinesis	(iii) Crossing­ over
D. Zygotene	(iv) Homologous chromosomes separate

1. A-­(iii), B-­(iv), C-­(ii), D-­(i)
2. A-­(i), B-­(iv), C­-(ii), D-­(iii)
3. A-­(ii), B-­(iv), C-­(iii), D-­(i)
4. A­-(iv), B-­(iii), C-­(ii), D-­(i)

Q. Match list I and list II and select the correct answer.

$\begin{array}{ccc}& \text{List I}& \text{List II}\\ & \text{(Phase of meiosis)}& \text{(Event that occurs)}\\ 1& \text{Prophase I}& \text{Crossing over occurs}\\ 2& \text{Metaphase II}& \text{Sister chromatids migrate to opposite poles}\\ 3& \text{Anaphase I}& \text{Homologous chromosomes line up at equator in pairs}\end{array}$

1. 1, 2 , 3 correct
2. 1 correct
3. 1, 3 correct
4. 2, 3 correct

Q. Assertion: The reciprocal cross considering eye color in Drosophila did not follow the classical genetics ratio

Reason: Gene for eye color is sex-linked

1. Both assertion and the reason are true and the reason is a correct explanation of the assertion
2. Both the assertion and reason are true but the reason is not the correct explanation of the assertion
3. Assertion is true but the reason is false
4. Both the assertion and reason are false

Q.

Cell Division is initiated by

1. Centriole

2. Chromomere

3. Centrosome

4. Centromere

Q.

What happens to chromosomes towards the start of telophase?

Q. Onion root tip cells have 14 chromosomes in each cell. Can you tell how many chromosomes will the cell have at $G_1$ phase, after S phase, and after M phase? Also, what will be the DNA content of the cells at $G_1$, after S, and at $G_2$ $, if the content after M phase is 2C?

Q.

Where can early recombination nodules be found?

Q.

What is the basis of the division of prophase I?

Q. Crossing over takes place between which chromatids and in which stage of the cell cycle?

1. Non-sister chromatids of non-homologous chromosome at zygotene stage of prophase-I
2. Non-sister chromatids of homologous chromosome at pachytene stage of prophase-I
3. Non-sister chromatids of homologous chromosome at zygotene stage of prophase I
4. Non-sister cromatids of non-homologous chromosomes at pachytene stage of prophase I